The production of amines via a reaction scheme including a nitration step followed by a hydrogenation step has been known in the art for quite some time. Such a reaction scheme is applicable to the preparation of polyisobutyleneamines, which are useful as dispersant additives in motor fuels and lubricants. For example, U.S. Pat. No. 5,879,420 teaches reaction products of polyisobutenes having an average degree of polymerization P of from 10 to 100 and a double bond content E in the range from 60 to 90% which can react with maleic anhydride, wherein a value of E=100% corresponds to the theoretical value for the case where each molecule of the polyisobutene has such a double bond. This patent also teaches the reaction of these materials with oxides of nitrogen or mixtures of oxides of nitrogen and oxygen and their subsequent reduction to amine products, wherein said products are suitable as additives for fuels, in particular for gasoline engines, and for lubricants. Further, U.S. Pat. No. 6,069,281 discloses the preparation of organic nitrogen compounds, in particular of aminoalkanes, alkyloximes, alkylnitrones, or mixtures thereof, which have only one nitrogen-functional group and no alcoholic hydroxyl groups in the molecule, from nitro-containing reaction products of polymers of C2-C6 olefins with an average degree of polymerization P=5-100 and nitrogen oxides or mixtures of nitrogen oxides and oxygen, by hydrogenation of these reaction products. The invention also relates to particular mixtures of such aminoalkanes, alkyloximes and/or alkylnitrones and to individual compounds of these types themselves. The designated products are suitable as additives for fuels and lubricants. Further, U.S. Pat. No. 5,810,894 sets forth an oligomeric olefin monoamine for use as an additive in fuels and related products, and a method of producing the same. The oligomeric olefin monoamine is free of any undesirable halogens such as would be introduced in a prior art method comprising halogenation and subsequent reaction with amine. The method of making the oligomeric olefin includes the steps of forming an oligomeric olefin epoxide, converting the epoxide to an alcohol, and then converting the alcohol through the use of ammonia to an oligomeric olefin monoamine.
Generally, the methods of the prior art which are used to produce polyisobutyleneamines, via a nitration reaction followed by a hydrogenation step, do not produce a final polyisobutyleneamine product having as high of a total amine content as is desired. This is due in large measure to the incomplete reduction of the nitrogen-oxygen species present as a raw material in the reduction step. Thus, if a method for producing polyisobutyleneamines via a reaction scheme comprising a nitration step followed by a reduction step were available in which the total amine content of the final product could be increased to more closely approach the theoretical maximum value, such method would be of great value, because the performance of the final product is directly related to the total amine content, and because the presence of unreduced nitro groups in the final product is undesirable.